`sig
val char_of_digit : int -> Core_kernel.Std.Char.t
val invalid_range : digits:int -> max:int -> i:int -> 'a
val blit_string_of_int_4_digits :
Core_kernel.Std.String.t -> pos:int -> int -> unit
val blit_string_of_int_2_digits :
Core_kernel.Std.String.t -> pos:int -> int -> unit
val blit_string_of_int_3_digits :
Core_kernel.Std.String.t -> pos:int -> int -> unit
val parse_two_digits : Core_kernel.Std.String.t -> int -> int
val parse_four_digits : Core_kernel.Std.String.t -> int -> int
end`